Fluorine-containing sulfonylimide salts are useful compounds in a wide variety of fields, and are used as electrolytes, as additives added to the electrolytes of fuel cells, and as selective electron withdrawing materials and the like (see Patent Document 1).
Various processes have been proposed for synthesizing fluorine-containing sulfonylimide salts. For example, Patent Document 2 proposes a process for producing a fluorine-containing sulfonylimide salt by reacting a fluorine-containing sulfonylimide onium salt with an alkali metal compound. Specifically, in Patent Document 2, triethylammonium N-(fluorosulfonyl)-N-(trifluoromethylsulfonyl)imide and an aqueous solution prepared by dissolving lithium hydroxide monohydrate are mixed together under normal pressure, and the solvent is then distilled to dryness to obtain lithium N-(fluorosulfonyl)-N-(trifluoromethylsulfonyl)imide.
Further Patent Document 3 discloses that by adding a tetrahydrofuran solution of lithium hydroxide monohydrate to a tetrahydrofuran solution of an ammonium cyclo-perfluoroalkane-1,n-bis[sulfonyl]imide, and then boiling for 120 minutes, a lithium cyclo-perfluoroalkane-1,n-bis[sulfonyl]imide is obtained.